Apparatus for ultrasonic processing of materials

ABSTRACT

Apparatus and processes are disclosed for treating materials by exposure thereof to sonic or ultrasonic oscillations produced by oscillating plates which form part of a processing chamber and which are each activated by a plurality of transducers adjacent thereto. The transducers are excited by an electronic circuit capable of driving each transducer at selectable frequencies, phase relationships and amplitudes. The invention also comprises processes for the treatment of materials by exposure thereof to oscillating plates excited at predetermined combinations of frequencies, phases and amplitudes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to apparatus and processes forthe treatment of materials. More specifically, the invention disclosedherein relates to apparatus and processes for processing materials bythe exposure thereof to sonic and ultrasonic oscillations.

2. Description of the Prior Art

Sonic and ultrasonic processing devices for the treatment of materials(usually a medium in the liquid phase) are well known in the prior art.Generally, they can be characterized as either static (or batch)processors or continuous, flow-through ultrasonic processors. As will beunderstood by those skilled in the art, the term "ultrasonic" sometimesis used to refer to frequencies in excess of 20,000 H_(z) and the term"sonic" sometimes refers to frequencies less than 20,000 H_(z). However,for the purpose of the present invention it will be understood that theterm "ultrasonic" will be used generally herein to refer to allfrequencies. Ultrasonic processors, as that term is used herein,generally refers to devices which can produce, within a material ormedium, oscillations at a predetermined frequency, which oscillationsare used generally for treatment of the material by processes such asemulsification, solubilizing, cleaning, etc.

Static processors usually comprise a processing chamber for containingthe material to be treated and at least one plate or transducer forbeing oscillated at a predetermined frequency and for oscillating saidmaterial.

Continuous, flow-through processors known in the prior art generallycomprise a processing chamber through which the material to be processedflows or circulates and at least one transducer for being in contactwith the processing chamber or flowing material and for being oscillatedat a predetermined frequency.

However, such prior art ultrasonic processors are limited in size andnot suitable for use with materials comprising liquid having large solidparticles therein such as, for example, a "slurry" or "pulp" of mineralore mixed with a liquid leaching compound. Thus, prior art ultrasonicprocessors are unavailable for either high volume processing or forefficient use in extraction of minerals from ores. The essential reasonfor such unsuitability of prior art devices is their inability toprovide large ultrasonic processing chambers. This limitation is aresult of the inherent limitations of prior art ultrasonic processorswith respect to the manner in which they act upon materials to producethe desired effects.

It is known that the achievement of the desired results by ultrasonicprocessors is not a gradual process but rather a threshold effect. Thatis, until a certain power intensity or threshold of ultrasonicoscillations is reached, the desired result is not achieved. Theamplitude or intensity at which this effect occurs is called the"threshold level." Increasing the amplitude or intensity of sonic energysubstantially above the threshold level does not usually enhance theresults to any great degree.

In practice, threshold levels may be fairly easily utilized and achievedin static processors since the cavitation effects, characterized bytremendous differential pressures, can occur within all areas of thematerial to be processed within two to three inches of the transducersurface in a matter of seconds.

The achievement of threshold effects in continuous flow-throughprocessors is not so easily accomplished in view of the obvious timefactor causing the material to be exposed to the ultrasonic oscillationsfor only a limited period of time (determined by the rate of flow). Incontinuous flow processing it is necessary to cause the cavitationaleffects to impinge upon all required sites within the material beingprocessed while insuring that the threshold effect power level isapplied to these sites rapidly to enable as high a flow rate aspossible.

Certain continuous flow processing apparatus are known in the prior artwhich minimize this time factor by creating a very small processingvolume having a large surface area in contact with the oscillatingplates which are separated by an extremely small distance on the orderof point 1-25 millimeters. An example of one such prior art device isshown in U.S. Pat. No. 4,071,225, dated Jan. 31, 1978. Such prior artcontinuous flow processors are obviously less efficient than larger onesand are unsuitable for the processing of large volumes of materials,particularly in the mining or minerals industry where the solid phaseparticulates exceed the maximum spacing of transducers in these priorart continuous flow processors.

Thus, it is one object of the invention disclosed herein to provide anultrasonic, continuous flow processor having processing chambers greaterin size then prior art processors and where the oscillating plates may,for example, be separated up to the order of magnitude of 120 inches,this spacing being a function of the frequency used in the processor.

Presently, metallic ores are chemically leached to extract the metaltherein without the aid of ultrasonic processors. For example, silverand gold ores have been leached with cyanide. However, this process is afunction of surface oxidation of the silver and gold. With adequatecleaning of the surfaces of these ores, the productivity of suchleaching techniques can be considerably increased. Continual cleaning ofthe surface as may be effected by ultrasonic processors will producefresh surface to work with, therefore, an increase in the efficiency ofleaching processes will serve to increase ore recoveries and decreaseextraction times considerably. Uranium extraction can also be enhancedin this way. Such continual cleaning also enhances dissolution of oxygenin leaching of gold, silver and uranium ores, thus having furtherbeneficial effects as will be apparent to those skilled in the arts.Accordingly, it is a further object of this invention to provide anultrasonic, continuous flow processor for use in extraction of mineralores.

Furthermore, prior art ultrasonic processing devices do not incorporatemeans to vary the frequency, amplitude and/or phase of oscillationsproduced in oscillating members. While prior art processors such as thatdisclosed in the aforementioned U.S. Pat. No. 4,071,225 are known to mixfrequencies of transducers within one ultrasonic processing device, eachtransducer used is such device is fixed to oscillate only at onepredetermined frequency and with no variation of phase or amplitudeamong the various transducers. Accordingly, it is another object of thisinvention to produce means for controlling and effecting frequency,amplitude and/or phase variations in ultrasonic processors.

Heretofore, ultrasonic processor devices have not been capable ofoptimizing the power drawn into the moving pulp stream in order tobetter match the operating impedance of the material being processed.This resulted in an inefficient operation of prior art devices.Accordingly, a further object of the invention is to provide means formaximizing an ultrasonic effect within an ultrasonic processor bymaximizing power transfer to the material being processed.

SUMMARY OF THE INVENTION

The preferred embodiment of the invention disclosed herein comprisesapparatus and process for the ultrasonic treatment of materials. Theapparatus comprises a processing chamber having an input thereto and anoutlet therefrom for said material to flow therethrough, said chamberbeing comprised in part of two opposed plates for being oscillated bytransducers excited in a predetermined manner by an electronic circuit.The circuit enables the plates to be oscillated at predeterminedvariable frequencies, with a predetermined relative phase relationshipand at predetermined amplitudes. The preferred embodiment furtherenables the frequency, phase and amplitude of the plates to be variedwithin a predetermined range.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention as well as additionalobjects and advantages thereof will become apparent upon considerationof the detailed disclosure thereof which follows, in conjunction withthe following drawings wherein:

FIG. 1 is a side elevational, cross-sectional diagrammatic view of thepreferred embodiment of the processing unit and circuitry of theinvention;

FIG. 2 is a more detailed side elevational, cross-sectional view of thepreferred embodiment of the processing unit shown in FIG. 1;

FIG. 3 is front elevational, cross-sectional view of the processing unittaken along the lines 3--3 of FIG. 2;

FIG. 4 is a plan view of the processing unit taken along lines 4--4 ofFIG. 2;

FIG. 5 is a plan view of the spacer of the processing unit taken alonglines 5--5 of FIG. 2;

FIG. 6 is a schematic circuit diagram of the frequency selector portionof the invention;

FIG. 7 is a schematic circuit diagram of the phase control portion ofthe invention.

FIG. 8 is a schematic circuit diagram of the power control portion ofthe invention;

FIG. 9 is a schematic circuit diagram of the power drives portion of theinvention;

FIG. 10 is a schematic timing diagram showing various representativesignals produced by the invention.

FIG. 11(a) is a schematic wave diagram showing the relative positions ofthe opposing oscillating plates of the transducers at 0° phasedifference.

FIG. 11(b) is a schematic wave diagram showing the relative positions ofthe opposing oscillating plates of the transducers at 45° phasedifference.

FIG. 11(c) is a schematic wave diagram showing the relative positions ofthe opposing oscillating plates of the transducers at 90° phasedifference.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the invention disclosed herein is shown inFIG. 1 as a system and is generally designated by the numeral 10 havinga processing unit 12 and an electronic pulse-power drive control unit14.

Processing unit 12, more specifically shown in an elevationalcross-section view in FIG. 2 comprises a top unit "A" generallydesignated by numeral 16, a bottom unit "B" generally designated bynumeral 18 and a spacer 20 interposed therebetween. Top unit 16 is, inthe preferred embodiment, identical to bottom unit 18 and, therefore,only elements within unit 16 will be discussed in detail herein, itbeing understood that the preferred embodiment incorporates both units16 and 18.

Unit 16, best seen in FIGS. 2 and 3, includes housing 22 in the form ofa rectangular parallelpiped enclosed on 5 sides and open at side 24.Housing 22 may be of a one-piece molded or stamped constructionutilizing metal or some other suitable material. Housing 22 is providedwith a peripheral flange 26 having a plurality of apertures 28 thereinfor receiving bolts for securing housing 22 to spacer 20 and unit 18, aswill be more fully apparent below.

Housing 22 is for encasing a plurality of transducers (hereindesignated) 30, 32, 34 and 36 therein. These transducers 30, 32 34 and36 will sometimes hereinafter be referred to as X_(A) transducersindicating their position within top unit "A" as opposed to X_(B)transducers which are those within bottom unit "B". The X_(A)transducers 30, 32, 34 and 36 are all identical in the preferredembodiment to each other and to the X_(B) transducer and are moreclearly seen in FIGS. 3 and 4. These transducers 30,32,34 and 36 are, inthe preferred embodiment, magnetostrictive ferrite transducers which areknown in the art to have power output of less than eleven (11) watts persquare centimeter of transducer piston area. made from ceramic typematerial such as barium titanate or lead zirco-titanate and theirradiating surfaces are at 38, 40, 42 and 44 respectively. Alltransducers disclosed herein are driven or caused to oscillate within apredetermined frequency range in a predetermined manner by electronicpulse-power drive-control unit 14 as will be more fully explained below.The frequency range of the preferred embodiment is 1 to 99,900 H_(z),however, while the frequency is adjustable within this range (as will beexplained below), any one set of X_(A) and X_(B) transducers may only befrequency variable within a portion of this range (for example, 20kH_(z)). Thus, the range of frequency variations which may be producedby the preferred embodiment is dependent upon the transducers chosen andif a greatly different frequency is desired the set of X_(A) and X_(B)transducers should be installed.

Each radiating surface 38, 40, 42 and 44 is bonded by a suitable bondingmaterial to the back 46 of vibrating plate or diaphragm 18 of unit A(sometimes hereinafter referred to as plate "A"). Those skilled in theart will realize that if a bonding material is used to secure theradiating surfaces of the transducers to back 46 it must be compatiblewith the material of the X_(A) transducers and of plate 48 and must beable to transmit the oscillations of each transducers' radiating surfaceto plate 48 without significant degradation. The plate 48 and thetransducer 30, 32 34 and 36 should have similar and compatiblecoefficients of expansion.

Plate 48 has a working surface 50 which may be of a coating materialother than that of plate 48. Surface 50 should be an abrasion andcorrosion resistant material capable of withstanding the highly abrasiveenvironment within processing chamber 52 to which it (surface 50) willbe subjected, such as non-magnetic stainless steel, nickel, titanium,tantalum or aluminum oxide. Plate 48 is the same size as flange 26 andis provided with apertures in alignment with apertures 28. A spacer 54is interposed between flange 26 and the back 46 of plate 48 in order toinsulate housing 22 from the oscillations of plate 48.

The ends of all X_(A) transducers 38a, 40a, 42a and 44a oppositeradiating surfaces 38, 40, 42 and 44 respectively, are bonded to abacking plate 56 which is, in operation, abutted against the insidesurface 58 of housing 22. Consequently, those skilled in the art willrealize plate 56 must be of a vibration insulating material so as toavoid needless and inefficient transfer of energy to housing 22 and awayfrom working surface 50. The depth 60 of housing 22 is equal to thecombination of the thickness of plate 56 and the length of an X_(A)transducer in order to effect a tight fit between all components whenunit 16 is assembled.

Those skilled in the art will realize that the apparatus disclosedherein will function properly without housing 22 and backing plate 56.If the transducers are brazed or otherwise suitably bonded to theoscillating plates then there is no need for the housing and plate.

Each X_(A) transducer is wound with a predetermined number of coils ofsuitable teflon coated wire 62 as shown schematically on transducer 30in FIGS. 2 and 4 and transducer 36 in FIG. 3. Those skilled in the artwill understand that the impedance of each transducer coil should bematched with the impedance of its driving circuit for efficient powertransfer. (The windings are not shown on transducers 32, 34 and 36 inorder to clarify the the drawing.) All transducers are wound in paralleland each pair of ends 64 and 66 are connected to respective drivecircuits as will be more apparent below with respect to FIG. 9. Wire 62has end leads 64 and 66 which terminate at a point (not shown) externalto housing 22. The means by which leads 64 and 66 pass through housing22 is purely conventional and is not shown herein.

Processing unit 12 includes a processing chamber 52 formed by surface50, the working surface 70 of the oscillating plate 72 of unit 18, andthe interior surface 74 of spacer 20. The shape of processing chamber 52is more clearly seen in FIG. 5 which shows a plan view of spacer 20including input port 76 and outlet port 78. Ports 76 and 78 may bethreaded to be compatible with pipes (not shown) for feeding unprocessedmaterial into chamber 52 and receiving processed material therefromafter it has been subjected to ultrasonic oscillations within chamber52. Spacer 20 should be a material which will not absorb the ultrasonicenergy within processing chamber 52. It should also be resistant toabrasion as well as chemically inert. For example, spacer 20 may beconstructed from a non-metallic material, plastic or elastomer.

The depth 53 of processing chamber 52 is obviously equal to the heightof spacer 20. In operation of the preferred embodiment, spacer 20 may beeither a single unit having the desired height or may comprise severallayers of spacers having predetermined thicknesses which may be combinedto produce the desired height. This height, and therefore depth 53, is afunction of the power and frequency at which the transducers will beoperated. Depth 53 may, for example vary from the order of 1 inch at 20KH_(z) to the order of 120 inches at 5 KH_(z). The greater the depth,the greater the power that must be applied to the oscillating plates.

FIG. 3 discloses a side elevational cross-section view of FIG. 2 takenalong lines 3--3. FIG. 3 more clearly shows X_(A) transducer 36 andbiasing magnet 80 associated therewith in a manner well known to thoseskilled in the art for producing a necessary bias to enable full andefficient utilization of magnetostrictive transducers. The biasingmagnets shown need not be utilized if an electrical DC bias is appliedto the transducers. Bolts 82 are also schematically shown in FIG. 3indicating the means by which the various component elements ofprocessing unit 12 are joined.

FIG. 4 is a plan cross-section view of FIG. 2 taken along line 4--4 andshows the shape of processing chamber 52, apertures 28, backing plate 56and X_(A) transducers 30, 32, 34 and 36. Wire 62 and end leads 64 and 66are diagrammatically shown wrapped around the N and S poles oftransducer 30 in a pattern well known to those skilled in the art.

Referring now to FIGS. 1 and 6 through 10, the operation of electricalpulse-power drive control 14 will be explained. As seen in FIG. 1,control 14 consists essentially of a frequency selector circuit 100,phase control circuit 102, power control circuit 104 and power drivercircuite 106. Each of these circuits is more specifically described inFIGS. 6, 7, 8 and 9 respectively. FIG. 10 shows timing diagrams linkingvarious circuit operations.

Referring now to FIG. 6, there is shown a schematic representation offrequency selector circuit 100 including 2000 MH_(z) oscillator 200,binary coded decimal (BCD) rate multiplier network 202, BCD switches204, 205, 206, 207, 208 and LED display section 210.

Oscillator 200 produces digital pulses at its output along line 212 tothe rate multiplier network 202. Oscillator 200 may be of conventionalconstruction, however, the design of oscillator 200 in the preferredembodiment employs an integrated circuit (for example, a 4001 Quad NORGate) wired as shown in FIG. 6.

Rate multiplier network 202 comprises five cascaded integrated circuitchips 214, 216, 218, 220 and 222, each a 4527 BCD Rate Multiplier, allwired as shown in FIG. 6. Rate multipliers 214, 216, 218, 220 and 222are each controlled respectively by BCD switches 204, 205, 206, 207 and208. These BCD switches may, for example, be thumbwheel-type adjustableswitches providing a BCD output from each switch as a function of thesetting thereon. Switches 204, 205, 206, 207 and 208 are alsorespectively wired as shown with LED drivers 224, 226, 228, 230 and 232which are themselves respectively wired to drive LED chips 234, 236,238, 240 and 242. The wiring of the various components of FIG. 6 isconventional and is therefore not discussed in detail herein.

Switches 204, 205, 206, 207 and 208 simultaneously provide a signal totheir respective rate multiplier and LED driver and, therefore, theoutput displays by LED display 210 is related to the output of ratemultiplier network 202. As will be more fully explained below, the LEDdisplay section 210 will display, on chips 234, 236, 238, 240 and 242,the frequency F_(X) ultimately provided to both X_(A) and X_(B)transducers. Simultaneously with this display, the output of the ratemultiplier network 202 is herein designated F₀ on line 250 where,because of the cascaded design of network 202, F₀ =20 F_(X). Thenecessity for providing a signal in the preferred embodiment at amultiple of F_(X) is related to the ability of the apparatus disclosedherein to provide differential phase oscillations between X_(A) andX_(B) transducers, as will be more fully explained below.

Referring now to FIG. 7, there is shown in more detail a schematicdiagram of phase control unit 102. Phase control unit 102 comprisesphase A circuit 300, a phase B circuit 302 and a phase display circuit304.

Phase A circuit 300 is essentially a divide by 20 counter comprising anintegrated circuit decoded output decimal counter 306 (for example a4017 Decimal Counter) to divide the F₀ input from frequency selector 100by ten, and a divide by 2 flip flop 308 (for example, a 4013 Dual D FlipFlop). Those skilled in the art will understand that the output Q_(A) ofphase A circuit 300, on line 310, is a digital series of pulses havingthe same frequency as that displayed on LED display 210 of FIG. 6.

Counter 306 is wired as shown in FIG. 7, its output lines 0-9 beingconnected respectively to contacts on rotary switch 312-1. The tenthpulse going through counter 306 (i.e. the pulse at terminal number 9) isused as a clock pulse to trigger flip flop 308, thus producingalternately high and low output pulses Q_(A) having a duration of ten F₀pulses and a frequency F₀ ÷20=F_(X) (best seen on Line 3 FIG. 10)

Referring now to FIG. 11, the terms "phase difference", "phase relativeto" and "phase relationship" are most easily understood by examiningFIGS. 11(a,b,c). As shown in FIG. 11(a) the transducer plates are bothmoving in the same direction in real time at 0° phase difference.Conversely, as shown in FIG. 11(c) both plates are moving in oppositedirections when the phase difference is 90°. As illustrated in FIG.11(b) when the phase difference is 45° the plates are moving indifferent directions during one half of the cycle and in the samedirection during one half of the cycle.

Switch 312-1 is one plate of an 11 position ganged switch generallydesignated 312, with the remaining plates thereof being designated 312-2and 312-3 as shown. The terminals of each plate of the ganged switch 312are designated in increments of 9° going from 0° to 90° to represent avariable phase difference between the A and B sets of signals selectablewithin the range 0° to 90°.

The output of counter 306 and Q_(A) are utilized by phase B circuit 302to produce an output signal Q_(B) having the same frequency as Q_(A) butof different phase. The output signal Q_(A) goes through a one-shotmultivibrator 314 which produces an output pulse to reset flip flop 316(for example, a 4013 Dual D Flip Flop) while the output of counter 306is selectively (by means of switch 312-1) applied to the clock input offlip flop 316. As will be understood by those skilled in the art, theresult is that the output Q_(B) of flip flop 316 is shifted in time fromQ_(A) as more clearly seen in lines 3, 4 and 5 of the timing diagramFIG. 10.

The output Q_(B) of flip flow 316 is wired to switch 312-2 havingcontacts 2-11 (designated by numerals 9-90 representing degrees) thereofshorted while contact 1 is connected to Q_(A) via line 318.Consequently, when switch 312-2 is in position 1 (marked 0°) the outputof phase B circuit 302 on line 320 is Q_(A) and both X_(A) and X_(B)transducers will be oscillating in phase, i.e. phase difference =0° andthe plates consequently move simultaneously in the opposite directionsat each instant of time. A phase difference of 90° is representative ofa relative movement of the two plates in the same direction at eachinstant of time. The greatest effects of cavitation disruption and themaximum power transfer to the medium being processed have been observedto fall between 30° to 60°. When switch 312-2 is in any other position,its output is dictated by the output of flip flop 316 which is afunction of the position of switch 312-1. Those skilled in the art willunderstand that the phase difference between Q_(A) and Q_(B) can bestepped from 0° to 90° in 9° increments.

A visual display of the phase difference between Q_(A) and Q_(B) isprovided by phase display 304. Switch 312-3, ganged to switches 312-1and 312-2, enables certain combinations of inputs of LED drivers 330 and332 (each, for example, a 4511 BCD to 7 segment latch, decoder/driver),in turn causing LED chips 334 (tens) and 336 (units) to firerespectively and display that number corresponding to the pre-wiredcombinations necessary to reflect phase difference increments from 0° to90° in 9° increments. The detailed wiring to effect such results isconventional and therefore not discussed herein.

The present invention utilizes phase relationships between theoscillating plates to achieve doppler and other ultrasonic effectssimilar to those occurring in prior art ultrasonic processors havingextremely thin processing chambers. However, the present inventionneither requires nor depends upon reflections of ultrasonic oscillationsfrom surfaces opposite the oscillating source. The phase differencebetween the oscillating plates therefore eliminates the necessity forreflections in prior art processors and enables much larger (deeper)processing chambers. The depth of the chambers which are made possibleby the present invention depends upon the power and frequency of thesignals applied to the transducers--lower frequencies generally enablesdeeper chambers, all other parameters being equal.

The phase difference between the oscillating plates effectively producesa plurality of frequencies similar to the result obtained due to dopplereffects in thin-chambered prior art ultrasonic processors. The phasedifference increases the number of rarefactions and compressions set upwithin the medium being processed and thus tends to remove standingwaves, thus improving and increasing the ultrasonic energy gradientwithin the processing chamber. The power or energy transferred to theprocessing chamber may be sensed by a conventional power meter (notshown). As stated above, the maximum power transfer appears to occurbetween 30° and 60° phase difference. This power transfer may be furtherenhanced by operation under increased pressure.

The outputs Q_(A) and Q_(B), each a digital series of pulses having afrequency=F_(X), are applied to power control unit 104, morespecifically shown in FIG. 8, which effects power control of the pulsesapplied to the transducers through pulse width modulation. Unit 104 isdivided into two identical sections: X_(A) transducer power section 402and X_(B) transducer power circuit 404 for producing power controlsignals for the X_(A) and X_(B) group of transducers respectively. Inview of the identity between sections 402 and 404, only the former willbe described in detail herein. It will be understood that the circuitsdisclosed herein may, if desired, be employed to vary the duty cycle ofeach single transducer in an ultrasonic processor rather than groups oftransducers.

Section 402 comprises counter 406 (for example, a 4017 Decimal Counter)which receives an F₀ clock input at its clock terminal from line 250 vialine 408. Counter 406 also receives at its clock enable terminal theQ_(A) output of phase control unit 102 through an inverter 410. TheQ_(A) signal is also provided to one-shot multivibrator 412, the outputof which sets flip flop 414 (for example, a 4013 Dual D Flip Flop) whenQ_(A) goes high. The decoded outputs of counter 406 occur at each of theten pulses after the clock enable pulse (since Q_(A) remains high forten F₀ pulses) and go through an 11 position rotary switch 416-1 (notshown), through inverter 418 and one-shot multivibrator 420, the outputof which is provided to the reset terminal of flip flop 414. Switch416-2 (not shown), ganged to switch 416-1, receives the Q output of flipflop 414 and connects it in parallel to buffer amplifiers 420, 422, 424and 426 which ultimately, as will be shown below, provide power controlsignals for X_(A) transducers 30, 32, 34 and 36, respectively.

The clock input frequency to counter 406 is F₀ =20 F_(X) and thus duringthe time Q_(A) is high at the clock enable terminal of counter 406, theten outputs of the counter will range in 5% increments from zero and 5%(at the output terminal marked 10) to 50% (at the output terminal marked100). The numbers applied to the output terminals are arbitrary andmerely indicative of a "full-scale" (i.e. 50% on time) duty cycle beingequal to 100.

When Q_(A) goes high it triggers a one-shot multivibrator 412 which setsflip-flop 414 causing its Q output to go high. The Q output is made lowwhen flip-flop 414 is reset by one-shot 420 which fires in response to aselected output of counter 406. Thus, the Q output of flip-flop 414 mayhave a duration from zero to whatever duration Q_(A) has (which in thepreferred embodiment is a maximum of 50% on-time since Q_(A) remainshigh for 10 Clock pulses and low for 10 clock pulses).

Those skilled in the art will understand that the circuit of section 402provides output signals (to the transducers on lines 430, 432, 434 and436) which have selectively variable duty cycles depending upon theposition of switch 416-1. For example, when switch 416-1 is set at theposition marked 60 the reset signal is applied to flip-flop 414 on thesixth clock pulse after the clock enable pulse. This results in the Qoutput of flip-flop 414 staying high for 6 pulses out of the ten pulseduration of Q_(A), thus providing drive signal to the X_(A) transducershaving a duty cycle of 60% as schematically shown on line 7 of FIG. 10.The output of line 430 (connected to X_(A) transducer 30) inrelationship to the output of corresponding line 440 (connected to oneof the X_(B) transducers) is shown more clearly on lines 7 and 8 oftiming diagram FIG. 10. While these output signals are represented ashaving a 60% duty cycle, it is clear that a phase difference existsbetween the two sets of signals. (Note that FIG. 10 does not necessarilyrepresent the proper polarity of the various signals and is intended tobe merely representative of timing and phase variations).

The preferred embodiment of the invention utilizes means for enablingthe apparatus disclosed herein to have difficult duty cycles applied tothe oscillating plates. Thus, plate 48 transducers may be excited by a50% duty cycle while plate 72 transducers may simultaneously be excitedby a 30% duty cycle. The advantages offered by such flexibility aresignificant. It has been found, for example, that the mere difference induty cycles applied to plates 48 and 72 (all other parameters being thesame) can produce different effects upon the material in the processingchamber. Thus, one set of duty cycles (e.g. 50% on plate 48 and 30% onplate 72) may produce a stable emulsion (if the apparatus is used foremulsification) while a different set of duty cycles may produce anunstable emulsion.

Referring now to FIG. 9 showing a power driver circuit 500, the furtherprocessing of the output signal on line 430 is explained.

Power driver circuit 500 is one of several identical power drivercircuits in power driver unit 106 shown in FIG. 1. Each transducerutilized in the preferred embodiment has one such power driver circuit500 associated therewith. For clarity, therefore, only one such circuitis shown in FIG. 9 and is more specifically described herein.

The output of line 430 of FIG. 8 is associated with the number oftransducer 30 in the A section 16. The signal on line 430, more clearlyseen on line 7 of timing diagram FIG. 10, is amplified in the circuitshown in FIG. 9 to provide pulse power to transducer winding 60 throughleads 64 and 66 (corresponding to numerical designations on FIG. 2) at afrequency equal to that shown on frequency display 210. The pulsing ofthe transducers enables a greater power input because of the absence ofa temperature rise in the transducers and because of the short drivetime. Any requisite cooling of the transducers is also effected by theslurry or material being processed.

FIG. 9 shows a cascaded transistor array comprising transistors 501, 502and 505 which turn on high speed output drive transistor 506 when theoutput signal on line 430 is low. The result is excitation of theassociated transducer in a manner well known to those skilled in theart.

Transistors 508 and 511 function as a current clamp to limit the maximumcurrent in the transducer windings to prevent saturation. Capacitor 510is placed across the transducer windings to improve the power factor.Each output transistor 506 has associated therewith a "snubber" networkcomprising capacitor 512, diode 514 and resistor 516 to extend the safeoperating area of transistor 506. Transistor 505 has associatedtherewith, as shown, capacitor 520 and resistors 522 and 524 to form aresistor and capacitor commutation network. Other resistors shown inFIG. 9 are not enumerated herein since their function and relationshipto the circuit will be understood by those skilled in the art.

Power transfer from the plates to the material in the processing chamberis affected by the impedance of the material, which impedance varies asa function of flow rate, particulate size, pressure, etc. Power meters(not shown) may be secured to plates 48 and 72 in order to provide theuser with an indication of power being transferred to the material beingprocessed. A user could then adjust input power appropriately to enableoptimizations of this power transfer even in a dynamic situation whenmaterial is flowing in the chamber. A microprocessor (not shown) may beemployed in functional interconnection with such a power meter or othersensors to act as a feedback controller to vary the different parametersof the invention in order to continuously maintain optimum powertransfer to the material.

Those skilled in the art will understand that there is a relationshipbetween the power input to the X_(A) and X_(B) transducers and theamplitude of oscillation of each plate 48 and 72. This relationship neednot be linear in order to achieve proper operation of the preferredembodiment disclosed herein.

Numerous uses of this invention are possible in order to enhanceultrasonic processing of various materials, mixtures, substances and thelike. This invention may be used for all known ultrasonic processingoperations at levels of efficiency considerably greater than those ofprior art ultrasonic processes.

Also, depending on the work operation to be performed, numerous otherembodiments of the invention may be used. For example, consider theproblem presented by a mineral ore coated with silica and iron oxide,and from which one wishes to extract the underlying metal such as gold,silver and the like. The separation of silica, the heavy fraction, fromthe ore by ultrasonic processing requires a relatively low frequency andhigh power level. The separation of the light fraction, iron oxide, maythen require a relatively higher frequency and lower power. Thus, thisis an example of a work operation requiring a sequential exposure of amaterial to a gradient of frequency and power. The invention disclosedherein may accomplish such a gradient of frequencies and powers and alsoof phase by being structured in a sequential format. That is, aplurality of processing chambers could be arranged in series so that theoutput from one would flow into the input of the next, and so on. Thetransducers associated with each processing chamber could be controlledin parallel from an electronic control unit which could, in accordancewith the principles disclosed herein, control the frequency, power andamplitude signals supplied to the sequentially arranged groups oftransducers. Possibly different transducers having different resonantfrequencies may be necessary in conjunction with the successiveprocessing chambers, depending upon the frequencies to which thematerial must be exposed. In this manner, the flowing material could beexposed to predetermined frequency and power gradients by operation ofthe first processing chamber at one set of frequencies and power levels,the next processing chamber at a higher (or lower) frequency and lower(or higher) power level, and so on. Thus, the mineral ore could becompletely processed in one pass through the sequentially arrangedprocessing chambers.

Throughout this description of the invention it will be understood bythose skilled in the art that the term "power" may be used variously todescribe either the power input to the plates or the power intensity towhich the material in the processing chamber is exposed. The powerintensity is a function of the total power input, the area size of thevibrating plates over which the power is dispersed, as well as thefrequency and phase of the oscillations.

Those skilled in the art will understand that numerous othermodifications and changes of the embodiments of the invention disclosedherein may be made without departing from the spirit and scope thereof.

What is claimed is:
 1. An apparatus for treating material with waveshaving an ultrasonic frequency having a minimum frequency of at leastone thousand (1,000) cycles per second (c.p.s.) and a power intensity ofless than forty (40) watts per square centimeter, comprising:aprocessing chamber for said material to be treated therein; two opposedplates in contact with said material in said chamber, said plates beingfor oscillation at an ultrasonic frequency and said plates beingdisposed substantially parallel to each other; means functionallyconnected to each of said opposed plates for causing each of saidopposed plates to oscillate at said frequency; means functionallyconnected to each to said opposed plates for varying the relative phaserelationship between each of said opposed paltes; and means functionallyconnected to each of said opposed plates for causing each of saidopposed plates to oscillate at an amplitude.
 2. An apparatus accordingto claim 1 wherein said opposed plates form two surfaces to saidprocessing chamber.
 3. An apparatus for treating material flowingtherethrough with waves having an ultrasonic frequency having a minimumfrequency of at least one thousand (1,000) cycles per second (c.p.s.)and a power intensity of less than forty (40) watts per squarecentimeter, comprising:a first and second parallel plate having thefront surfaces thereof facing each other and spaced at a distance forforming two sides of a processing chamber; a spacer interposed betweensaid parallel plates for forming the other, peripheral sides of saidprocessing chamber, said spacer having an input aperture for enablingsaid flowing material to flow into said processing chamber and an outletaperture for enabling said flowing material to flow out of saidprocessing chamber; at least one first transducer secured to the backsurface of said first plate and for producing oscillations thereof; atleast one second transducer secured to the back surface of said secondplate and for producing oscillations thereof; means functionallyconnected to and for causing each of said first and second transducersto oscillate at an ultrasonic frequency; means functionally connected toeach of said first and second transducers for varying the relative phaserelationship between said first and second transducer; meansfunctionally connected to and for causing each of said first and secondtransducers to oscillate at an amplitude; whereupon causing saidmaterial to flow through said processing chamber while causing saidfirst and second transducers to oscillate at said phase, amplitude andultrasonic frequency, said plates will oscillate thereby creatingoscillations within said material in said processing chamber therebytreating said material.
 4. An apparatus according to claim 3 whereinsaid input and outlet apertures are substantially linearly aligned. 5.An apparatus according to claim 4 wherein said plates are symmetricallydisposed about the alignment axis of said input and output apertures. 6.An apparatus according to claim 5 wherein said amplitude of oscillationof each of said plates is selectable within a range of amplitudes whilesaid material is flowing through said processing chamber.
 7. Anapparatus according to claim 5 wherein said relative phase relationshipbetween the oscillations of each of said plates is selectable within arange of relative phase relationships while said material is flowingthrough said processing chamber.
 8. An apparatus according to claim 5wherein said ultrasonic frequency of oscillations of each of said platesis selectable within range of frequencies while said material is flowingthrough said processing chamber.
 9. An apparatus for treating materialflowing therethrough with waves of an ultrasonic frequency having aminimum frequency of at least one thousand (1,000) cycles per second(c.p.s.) and a power intensity of less than forty watts per squarecentimeter, comprising:a processing chamber having an input thereto andan outlet therefrom for said material to flow therethrough and to betreated therein; two opposed rectilinear plates in contact with saidmaterial in said chamber, said plates being for oscillation and saidplates being disposed substantially parallel to each other, said platesforming two surfaces of said processing chamber and the front surfacesof said plates facing each other; a first plurality of magnetostrictivetransducers having their radiating surfaces secured to the backs of oneof said opposed plates; a second plurality of magnetostrictivetransducers having their radiating surfaces secured to the backs of theother of said plates; oscillating means for producing first signalshaving a frequency selectable within a range of ultrasonic frequencies;phase means functionally connected with said oscillating means andresponsive to the frequency output thereof for producing at least twofirst output signals having variable relative phase relationshipstherebetween; power signal means functionally interconnected with saidoscillating means, and responsive to the frequency output thereof, andfunctionally interconnected with said phase means, and responsive tosaid first output signals thereof, for producing a first and second setof power signals, said first set of power signals corresponding to oneof said first output signals and said second set of power signalscorresponding to the other of said first output signals, said first setof power signals corresponding in number to said first plurality oftransducers and said second set of power signals corresponding in numberto said second plurality of transducers, each one of said first set ofpower signals corresponding respectively to one of said first pluralityof transducers, each one of said second set of power signalscorresponding respectively to one of said second plurality oftransducers, said power signal means for controlling the magnitude ofpower within said first and second sets of power signals; a first set ofdriving means corresponding in number to said first plurality oftransducers and functionally interconnected with said first set of powersignals and said first plurality of transducers, each of said first setof driving means respectively responsive to said first set of powersignals for driving respectively said first plurality of transducers; asecond set of driving means corresponding in number to said secondplurality of transducers and functionally interconnected with saidsecond set of power signals and said second plurality of transducers,each of said second set of driving means respectively responsive to saidsecond set of power signals for driving respectively said secondplurality of transducers.
 10. An apparatus according to claims 1, 3 or9, having means for varying the pressure in said processing chamber. 11.An apparatus according to claim 9 wherein said input and outlet aresubstantially linearly aligned.
 12. An apparatus according to claim 9wherein said power signal means includes means for selecting the dutycycle of said first set of power signals within a range of duty cyclesand for selecting the duty cycle of said second set of power signalswithin said range of duty cycles.
 13. An apparatus for treating materialflowing therthrough with waves having an ultrasonic frequency having aminimum frequency of at least one thousand (1,000) cycles per second(c.p.s.) and a power intensity of less than forty (40) watts per squarecentimeter, comprising:a processing chamber having an input thereto andan outlet therefrom for said material to flow therethrough and to betreated therein; two opposed plates for being in contact with saidmaterial in said chamber, said plates being for oscillation and saidplates being disposed substantially parallel to each other; and meansfor causing each of said opposed plates to oscillate at said ultrasonicfrequency; the improvement comprising: means for varying the relativephase relationship between said opposed plates.
 14. An apparatus fortreating material flowing therethrough with waves having an ultrasonicfrequency having a minimum frequency of at least one thousand (1,000)cycles per second (c.p.s.) and a power intensity of less than forty (40)watts per square centimeter, comprising:a plurality of seriallyconnected processing chambers, each one having an input thereto and anoutlet therefrom for said material to flow therethrough and to betreated therein, the output of one processing chamber connected to theinput of the next successive processing chamber; a plurality of sets oftwo opposed, substantially parallel plates, said plurality of sets beingequal in number to said plurality of processing chambers, each set beingwithin one respective processing chamber, each of said opposed platesbeing in contact with said material within their respectively associatedprocessing chambers, said opposed plates within each of said sets forbeing vibrated at an ultrasonic frequency; means functionally connectedto each of said opposed plates for causing each of said plates withineach of said sets to oscillate at said ultrasonic frequency; phase meansfunctionally connected to each of said opposed plates for varying thephase relationship between said opposed plates within each of said sets;and means functionally connected to each of said opposed plates forcausing each of said plates to oscillate at an amplitude of oscillation.15. An apparatus according to claim 14 wherein said frequency meanscomprises:means for causing each plate of each of said sets of plates tooscillate at a frequency which varies among said sets and from one ofsaid sets to the next successive one of said sets for producing agradient of frequencies among said pluralities of said sets of plates.16. An apparatus according to claim 15 wherein said phase meanscomprises:means for causing one of said plates of each of said sets ofplates to oscillate at a phase relative to the other corresponding plateof each of said sets such that the phase difference between the platesof the next successive one of said sets produces a gradient of phasedifferences among said plurality of sets of plates.
 17. An apparatusaccording to claim 16 wherein said amplitude means comprises:means forcausing each plate of each of said sets of plates to oscillate with anamplitude of oscillation which varies among said sets and from one ofsaid sets to the next successive one of said sets for producing agradient of amplitudes of oscillations among said plurality of sets ofplates.